The present invention relates to a polyphase reluctance motor designed so that its torque characteristic with respect to an exciting current is linear, and a large output torque can be obtained at a high-speed rotation.
Although it is characteristic of a reluctance motor to output a large torque, a reluctance motor has scarcely been put to practical use because of its shortcomings such as low rotational speed, vibration, etc., except for uses for special purposes.
A known three-phase half-wave current-supply reluctance motor will be explained below with reference to FIG. 1. In FIG. 1, a reference numeral 16 denotes a stator armature formed of a silicon steel lamination. The stator armature has magnetic poles 16a, 16b, . . . 16f which are individually mounted with armature coils 17a-1, 17b-1, . . . 17f-1. A rotor 1 fixed to a rotary shaft 5 is formed with eight salient poles 1a, 1b, 1c, . . . 1h. When power is supplied to the armature coil 17b-1 and the armature coil 17e-1 situated in axial symmetry with the coil 17b-1 with the rotor 1 in a state as illustrated in FIG. 1, the rotor 1 is caused to rotate in a direction indicated by an arrow A. Then, when the rotor 1 rotates by an electric angle of 120xc2x0, power-supply is interrupted. Subsequently, when power is supplied to the coils 17c-1 and 17f-1 for an electric angle of 120xc2x0, the rotor 1 rotates in the same direction indicated by the arrow A.
As described above, when power is supplied to the armature coils in the order of [17a-1, 17b-1]xe2x86x92[17b-1, 17e-1]xe2x86x92[17c-1, 17f-1] . . . , the rotor 1 is rotated in the direction indicated by the arrow A.
Among the eight salient poles, two salient poles take part in a generation of rotational torque, with remaining six salient poles not taking part in the generation of rotational torque. But, if all salient poles simultaneously take part in the generation of torque, it is considered that the torque is increased accordingly. However, such a practical technique has not been developed yet.
Moreover, in the motor shown in FIG. 1, when power is supplied to the armature coils 17a-1 and 17d-1, magnetic poles 16a and 16d are attracted to a radial direction, so that the stator armature 16 is deformed due to an at traction force. When the rotor 1 is further rotated and power is supplied to the armature coils 17b-1 and 17e-1, magnetic poles 16b and 16e are attracted to a radial direction by means of magnetic poles 1a and 1e, and, likewise, the stator armature 16 is deformed.
When the rotor 1 is further rotated and power is supplied to the armature coils 17c-1 and 17f-1, magnetic poles 16c and 16f are attracted towards a radial direction by means of magnetic poles 1a and 1e, likewise causing the stator armature 16 to be deformed. In this manner, the deforming direction of the stator armature 16 successively shifts as the rotor 1 rotates. For this reason, such a deformation of which direction varies successively may give rise to a vibration, and may not keep constant an air gap between a salient pole and a magnetic pole. As a result, vibration produces noise during rotation of the motor and useful life of bearing in the rotary shaft of the rotor 1 to be shortened. Thus, in a motor of large-size and great-output, it is difficult to solve the aforesaid problems.
An object of the present invention is to provide a polyphase reluctance motor which is capable of obtaining a large output torque and suppressing vibration during operation.
To achieve the above object, the present invention provides a polyphase (N phase: N is a positive integer of 2 or more) reluctance motor comprising: a rotor of soft magnetic substance which is provided with n units of salient poles (n is a positive integer of 2 or more) of the same width and the same interval in circumferential direction thereof; a stator armature having mxc3x97n (m is an integer of 3 or more) units of magnetic poles which are formed by winding an armature coil around each two adjacent slots out of mxc3x97n units of slots formed at equal intervals in a circumferential direction thereof, said armature coils being connected to constitute a first-phase armature coil, a second-phase armature coil, a third-phase armature coil . . . , and an Nth-phase armature coil; means for rotatably supporting said rotor with respect to said stator armature so that said salient poles of said rotor and said magnetic poles of said stator armature confront each other through a slight gap; position detecting units for detecting rotational position of each salient pole of said rotor, and outputting first-phase, second-phase, third-phase . . . , and Nth-phase position detection signals of the same width, which are successively delayed by a predetermined period; semiconductor switching elements connected in series to each of said first-phase armature coil, second armature coil, third-phase armature coil . . . , and Nth-phase armature coil; a DC power source which supplies power to each of said phase armature coils through said semiconductor switching elements connected in series therewith; and a power-supply control circuit for controlling the activation of said semiconductor switching elements according to said first-phase, second-phase, third-phase . . . , and Nth-phase position detection signals outputted from said position detecting units, so that said first-phase armature coil may be supplied with power simultaneously with said second-phase armature coil during a section, said second-phase armature coil may be supplied with power simultaneously with said third-phase armature coil during a section, . . . , and said Nth-phase armature coil may be supplied with power simultaneotisly with said first-phase armature coil during a section.
Further, a first magnetic pole formed in said stator armature is magnetized simultaneously with a second magnetic pole adjacent thereto in a predetermined direction in a manner such that one is magnetized N pole while the other is magnetized S pole, then, the second magnetic pole is magnetized simultaneously with a third magnetic pole adjacent thereto in a predetermined direction in a manner such that one is magnetized N pole while the other is magnetized S pole, and then, the third magnetic pole is magnetized simultaneously with a fourth magnetic pole adjacent thereto in a predetermined direction in a manner such that one magnetized N pole while the other is magnetized S pole, thereby generating a leakage flux passing through one of two adjacent magnetic poles, of which confronting area with a salient pole is smaller, which is effective for developing a torque between the magnetic poles and the salient pole, and of which quantity is determined according to the quality of the magnetic flux passing through the other of the above two adjacent magnetic poles.
As the motor of the present invention has the construction as described above, the following effects can be obtained; (a) since output torque is generated by simultaneously exciting adjacent magnetic poles N and S poles to magnetically attract the salient pole, output torque can be obtained twice or three times as much as in the case of the conventional motor; (b) an air gap between the magnetic poles of the stator armature and the salient poles of the rotor is set within {fraction (1/10)} millimeter, so that a linearly proportional relationship can be established between current and output torque without torque saturation; therefore a large output torque can be obtained; and (c) all of salient poles of the rotor contribute to output torque without interruption, so that a large output torque can be obtained.